Because humans just existing produces far less pollution than humans producing a lot of stuff.

It’s trivial to say that a bunch of hunter-gatherers don’t pollute much but we’re not generally willing to relegate people to living in the stone age.

Our economic choices have a much larger impact on pollution than our personal choices do. Ideally we’d have a measure of pollution per consumption. Everyone would have a score that calculates the total pollution created by the entire supply chain that supports their choices. So if a mine in Africa is polluting so a Chinese guy can have a nice air condition, that should be counted for China; and if a factory in China pollutes so that a guy in the US can have a new Iphone, that should be counted for the US.

I’m not aware of any such data set. The closest proxy would be GDP or GNP. That essentially provides a measure of how much pollution the total lifestyle of that population produces.